Update May 13: the current Ulrich's total for academic, refereed, active journals is just over 27,000, which makes the DOAJ 5,000 only 18.5%, not over 20% of the world's journals as measured by Ulrich's. It is likely that both Ulrich's and DOAJ seriously underrepresent academic journals in China. Thanks to Stian Haklev for the figures.
The Directory of Open Access Journals (DOAJ) has just announced a list of milestones, including exceeding 5,000 journals. This is more than 20% of the world's scholarly peer reviewed journals, estimated at ~ 23,000 according to Ulrich's.
This is a conservative estimate. DOAJ is doing great work, but they are a small group, and kvetches from the open access community tend to center around the lag time it takes for new or converted journals to get through the DOAJ vetting process and be included in DOAJ.
If this is a concern for you - ask whether your local library, library consortia, or vendor who benefits from OA journals - is a member or supporter of DOAJ. As the notice points out, this support would be helpful to DOAJ to increase the services that people want of this popular site.
This post is part of the Dramatic Growth of Open Access series.